REVIEW ARTICLE

Pain management in abdominal surgery

Thomas M. Hemmerling1,2,3

Received: 20 May 2018 /Accepted: 26 August 2018# Springer-Verlag GmbH Germany, part of Springer Nature 2018

AbstractBackground Abdominal surgery has undergone major changes during the last two decades with a general shift from open,invasive surgery to closed minimally invasive surgery. Accordingly, pain management strategies have also changed, especiallywith the introduction of ultrasound-guided abdominal wall blocks. Despite laparoscopic abdominal surgery classified as minimal,pain can be quite significant and needs to be addressed appropriately.Purpose This narrative review focuses on adequate pain strategies for various types of surgery. The respective techniques aredescribed and examples of specific pain management strategies given. Advantages and disadvantages of techniques arediscussed. This review can serve as a sort of empirical guideline and orientation for the reader to develop their own strategyas well as bringing surgeons up-to-date with the latest anesthetic techniques.Conclusion Pain is not less or less relevant in minimally invasive surgery. New hallmarks of a multimodal pain strategy areabdominal wall blocks, either as single shot or continuously. Minor open surgery is best performed under a combination of loco-regional blocks and continuous sedation. Abdominal wall blocks, NSAIDs, and short-acting opioids given by nurses or as PCApresent the best multimodal pain strategy in abdominal surgery. Epidural analgesia and spinal anesthesia have become second-line options or are reserved for specific patient morbidities or surgical requirements.

Keywords Abdominal surgery . Painmanagement . Loco-regional anesthesia

For several decades, abdominal surgery has been mostly opensurgery. In the recent two decades, this has shifted towardsclosed and laparoscopic techniques. This has led to an adjust-ment of pain relief techniques and the development of newlocal or regional analgesic techniques. The most importantintroduction to anesthesia has probably been the developmentof the transversus abdominis plane block (TAP). Epidural an-algesia is still important pain relief for major abdominal sur-gery; however, its use has been limited by an ever increasingnumber of drugs used to interfere with blood coagulation: incontrast to orthopedic surgery, where even for emergency in-

terventions, delaysmight be acceptable until the effect of thesedrugs has worn off in order to allow for neuraxial techniques,delays of surgery cannot be accepted in abdominal emergencysurgery. In the elective setting, this might not necessarily be anissue since surgeons would stop these drugs to allow sponta-neous recovery of normal blood coagulation. Even so, thesheer number of drugs available, their often unpredictableeffect on blood coagulation and a general tendency for anes-thesiologists to look for alternative pain techniques, simply toavoid medico-legal issues, has decreased the use of epiduralanalgesia and weakened its status as the key analgesic com-ponent of pain treatment for major abdominal surgery.

The concept of combining different pain strategies, e.g., epi-dural analgesia plus non-steroid anti-inflammatory drugs(NSAIDs), has been firmly established in the center of perioper-ative pain relief. It needs no further justification. However, it hasalso been confirmed that the combination of pure pain strategieswith collective supplementary strategies, such as early food in-take, early mobilization, and tight blood sugar control, furtherenhances these pain strategies. Lastly, preoperative preparationof the patient, physically, medically, and psychologically, alsoplays into the hands of optimal perioperative analgesia.

* Thomas M. Hemmerlingthomas.hemmerling@mcgill.ca

1 Department of Anesthesia, McGill University, 1650 Cedar Avenue,Montreal, Canada

2 Division of Experimental Surgery, McGill University,Montreal, Canada

3 Department of Anesthesia, University of Montreal, CIUSSSMontreal-North, Montreal, Canada

Langenbeck's Archives of Surgeryhttps://doi.org/10.1007/s00423-018-1705-y

Let us separate this review on pain relief after abdominalsurgery into pain relief for minor or major surgery, as well asopen or closed surgery.

Pain relief for minor open abdominal surgery

Repair of umbilical or inguinal-femoral hernias, ischiorectalabscess, repair of pilonidal sinus or fistula, and hemorrhoidsurgery belong into this category.

It seems that the most appropriate analgesic strategy is toperform these types of surgery under local or loco-regionalblock.

For some anesthesiologists, a categorical patient’s wish BIwant to sleep^ rules out the feasibility of loco-regional tech-niques when, in fact, this is not a hindrance at all. It is allabout explaining to the patient the possibility of Bsleeping^during surgery in the same way as they would sleep at homeand reassuring them that the wish to sleep and not hear orfeel anything does not necessarily mean general anesthesia,but that this state is very feasible using continuous propofolsedation. In its most sophisticated form, this means target-controlled infusion (TCI) of propofol and establishment andmaintenance of the desired sedation level using continuousbrain monitoring, e.g., bispectral index monitoring. In addi-tion, explaining to the patient that in case of insufficientanalgesia during surgery, the surgeon can add local anesthe-sia, similar to a dentist when performing dental surgery un-der local anesthesia, can reassure almost all patients. It is allabout explaining in depth the advantage of loco-regionalanesthesia—speedy recovery, early discharge, no impact onurinary retention, excellent and long-lasting pain relief aftersurgery—while assuring that the Bblock^ will be performedunder short-term sedation and surgery under continuoussedation.

Using this strategy, most patients will choose this kind ofanesthesia. It seems that for this kind of surgery, the combina-tion of loco-regional block and sedation is the best combina-tion of efficiency of analgesia, fast recovery, and riskreduction.

However, it is not without pitfalls.These pitfalls can be categorized into problematic sedation

and problematic loco-regional blocks.Problematic sedation can occur specifically in young pa-

tients as well as in older patients. The right amount of se-dation can be difficult to judge and depends a lot on theexperience of the anesthesiologist as well as the patient’scondition and drug use. In a society where recreationaldrugs, such as marijuana, have achieved social and legalacceptance, anesthesiologists and surgeons need to questionthe patient carefully about any regular drug (ab)-use. Dailyuse of marijuana, for example, will often necessitate higherdoses of propofol to achieve a certain level of sedation—but

even this is not predictable. Performing these kinds of sur-gery under sedation can create the following unpleasant sce-narios: patients who get confused, patients who get dis-inhibited, or patients where even little doses of propofolcan cause respiratory distress. It is best to start with anempirical dose and adjust it rapidly according to either aclinical level of sedation or a level of sedation as determinedusing objective brain monitoring. It is often desirable to startthe sedation well before the incision, at the time of placingthe patient on the operating table, if possible. Also, in orderto avoid respiratory distress, oxygen supplementation canavoid respiratory distress and avoid having to lower thesedation level in order to secure proper oxygenation. Oneof the most important aspects of perioperative analgesiausing loco-regional blocks is the cooperation between sur-geon and anesthesiologist throughout the procedure. Failureof these techniques are often observed when surgeon andanesthesiologist do not know each other well and have littleexperience in managing these cases in this way.

The blocks most commonly used are abdominal wallblocks and amongst them mostly transversus abdominis planeblocks (TAP), rectus sheath blocks (RS), or block ofilioinguinal and iliohypogastric nerves. All these blocks areperformed using ultrasound guidance, and although common-ly referred to as loco-regional blocks, they should not be con-fused with neuraxial blocks; they are referred to as regionalblocks because the analgesia achieved performing them covera region but are not providing motor blockade. They are easyto perform, show a rapid learning curve, and provide excellentanalgesia during and after surgery for up to 24 h. However, theapplicability can somewhat be limited in very obese patients,specifically with blocks of the ilioinguinal and iliohypogastricnerves where nerve localization via ultrasound can be difficultor impossible.

Ideally, all blocks should be done outside of the operatingroom so as to decrease the stress for the patient. They shouldalso be performed under adequate monitoring. Emergencydrugs, such as ephedrine or atropine, should be ready to beused in prepared syringes. Obviously, an intravenous cannulashould be inserted and sedation for the block should be pro-vided. The most efficient sedation for these blocks is single-shot administration of intravenous midazolam or propofol ac-cording to the anesthesiologist’s preference; this author eitheruses 1–2 mg of midazolam or 0.25–0.5 mg/kg of propofol.Oxygen insufflation and mask ventilation should be available.

It is important, both for the anesthesiologist as well as thesurgeon, to familiarize himself with the abdominal wall anat-omy before performing any of the abdominal wall blocks [1].

Keep in mind that all these blocks need sufficient time towork: in this author’s experience, 15–30 min onset time iscommon after TAP and RS blocks. Therefore, sufficient timeshould elapse between the completion of the block and thestart of surgery.

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Specific surgeries

Open repair of umbilical hernia

The appropriate block technique both depends on the surgi-cal technique as well as the amount of defect. Smaller de-fects and an open surgical technique, which uses small intra-umbilical incision, can best be repaired using rectus sheath(RS) blocks [2].

This block (Fig. 1) provides analgesia of the terminalbranches of the 9th to 11th intercostal nerves between theinternal oblique and transversus abdominis muscles. Thesenerves run through the posterior wall of the rectus abdominismuscle towards the anterior cutaneous branch around the um-bilical area. Ultrasound guidance shows the various musclestructures. The probe is placed at 5–10 cm lateral of the um-bilical area and the internal oblique and transversus abdominismuscles are identified. The needle is advanced in-plane fromlateral to medial and superficial deep into the area in-betweenthe muscles. All abdominal wall blocks depend more on vol-ume than on concentration of local anesthetics: usually 20 mlof local anesthetic of a low concentration is sufficient.

This author prefers a combination of 10 ml of bupivacaine0.25% and 10 ml of lidocaine 1% in a mixture of 1:1 on eachside. Also, as a slight modification of the standard technique,15 ml is injected near the posterior border of the rectus sheath,whereas the remaining 5 ml of the mixture is injected justunderneath the anterior border of the rectus sheath.

The skin incision can easily be covered by small amountsof lidocaine 1% either applied by the anesthesiologist or thesurgeon immediately before incision. It is important for theanesthesiologist to be familiar with the surgical incision and

surgical technical habits. This type of analgesia works bestwith a small incision and insertion of a mesh graft, whichsecures itself with few stitches. Surgical techniques, whichcut below the umbilical area and necessitate extensive subcu-taneous dissection, might be more difficult to perform underloco-regional techniques alone.

Rectus sheath blocks provide analgesia for 12–24 h.Transversus abdominis blocks might be an alternative, es-

pecially if the dissection is more elaborate.Preparation of the patient is the same, monitoring, intrave-

nous cannula, single-shot sedation for performing the block.The injection site is between the transversus abdominal

muscle and the internal oblique muscle, more lateral than therectus sheath block (Fig. 2) [3].

This author places the needle in the middle or at level of theintended surgical incision and injects 25 ml of local anesthetic(same mixture as above) per side.

For both techniques, continuous sedation is appropriateduring surgery, as well as the availability of additional localanesthesia in form of lidocaine, as a sterile injection given bythe surgeon to supplement local anesthesia in areas of newlyoccurring pain during surgery.

Target-controlled infusion of propofol and brain monitor-ing seems to be the most sophisticated and precise way ofproviding adequate sedation; in younger patients, TCI is usu-ally started at 1.5 microg/ml, and adjusted according either toclinical sedation level and/or brain monitoring, with BISvalues of 75–85 usually showing adequate moderately pro-found sedation levels. In older patients, 0.5–1 microg/ml as

Fig. 1 US-guided RS block. Ultrasound image of the anatomicalstructures relevant for the rectus sheath block. Local anesthetic isinjected so as to lift up the rectus muscle

Fig. 2 US-guided TAP block. Ultrasound image of the anatomicalstructures relevant for the transversus abdominis block. Local anestheticis injected in-between the internal oblique and transverse abdominismuscle

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a target is the safer choice and adjustments are done as de-scribed before. It seems important that the sedation is alreadyunder way and the desired sedation level achieved before sur-gery starts.

Usually, these two blocks should provide sufficient painrelief after surgery as well. However, independently from oc-currence of intraoperative pain or not, some patients mightstill experience mild pain after surgery. Short-acting opioids,such as fentanyl in increments of 25–50 microg or ketorolac30 mg IV, are generally sufficient to provide excellent painrelief. The vast majority of patients, however, do not have painafter umbilical repair under TAP or RS and can go directly tothe ward without stopover in the recovery unit. Urination isnot impeded and discharge from the hospital is rapid.

In order to avoid prolonged stay in the recovery room dueto prolonged sedation, intraoperative sedation with propofolshould be stopped well before the end of surgery so that thepatient is well awake when surgery is completed.

Open repair of inguinal hernia

There are two possible block techniques for this kind of sur-gery: TAP block or blockade of the ilioinguinal andiliohypogastric nerves with the former being much more pop-ular recently, being easier to perform, and providing moreconsistent efficiency. There is still controversy which tech-nique is superior in terms of pain control during surgery andin the immediate postoperative period. Both block techniquesin comparison to neuraxial techniques seem to decrease theoccurrence of chronic pain after inguinal hernia repair [4].

The efficacy of TAP block for inguinal hernia repair seemsto depend as well of the proximity between the TAP blockneedle insertion site and the surgical site. The needle insertionsite should be located as caudal as possible. Also, sometimes25–30 ml of local anesthetic might not be sufficient and 40 mlof local anesthetic, e.g., bupivacaine 0.25%/lidocaine 1% in amixture of 1:1 is necessary.

Local skin analgesia can be provided by the surgeon justbefore surgery.

Initial studies showed a better pain relief of ultrasound-guided TAP versus blind ilioinguinal block techniques.However, recent advances and the use of US guidance haveincreased the success rate of this block. In comparison to TAPblocks, it needs lower volume of local anesthetics—in general,15 ml of the mixture described above is sufficient—and nowshows more reliable efficacy.

The ultrasound probe is placed obliquely on a line betweenthe anterior superior iliac spine and the umbilicus, superior tothe anterior superior iliac spine. The needle is placed in thefascial layer (Fig. 3). It occasionally, when performed toocaudally, causes a femoral nerve block; therefore, proper mo-tor function of the leg and the quadriceps should be checkedpostoperatively in all patients receiving a combined

ilioinguinal-iliohypogastric block. This is not a frighteningcomplication as long as the anesthesiologist explains this tothe patient—and the surgeon. It obviously can delay dischargefrom the hospital. This block might be an advantage for bilat-eral open hernia repair as it provides a bigger local anesthetictoxicity margin than bilateral TAP blocks by the reduced vol-ume necessary to achieve satisfactory analgesia—althoughpractically, local toxicity after bilateral TAP blocks has rarelybeen described [5].

Hemorrhoid surgery

Open hemorrhoid surgery can easily be performed under localanesthesia only—plus or without sedation [6].

Firstly, sufficient sedation should be achieved since theanal area is very sensitive. Depending on the area, 10–20 mlof a mixture of bupivacaine 0.25%/lidocaine 1% with epi-nephrine is sufficient; this mixture should be injected aroundthe anus in equal doses. Additional doses of this mixture—generally 5–10 ml—are then also inserted deeper, into theintersphincteric plane on four sides of the anus. Since the anusregion is highly vascularized, onset is very rapid and sufficientanalgesia can usually be provided within 5 min.

In comparison to spinal anesthesia, this technique carriesfar less side effects—headaches, dizziness, hypotension, uri-nary retention—as well as better and longer lasting pain reliefafter surgery. However, this technique necessitates a coopera-tive patient or deeper sedation in order to avoid movementduring surgery.

Surgery of ischiorectal abscess

This generally is not an ideal surgery for solely local anesthe-sia; depending on the degree of inflammation, the efficacy oflocal anesthetics is greatly reduced and therefore surgery can-not easily be performed under local anesthesia only. Spinalanesthesia or general anesthesia is better suited.

Surgery of pilonidal sinus-fistulas

Surgery of pilonidal sinus or fistulas should only be performedunder local anesthesia if the patient wishes so, if the layers offat and muscles are thin, sufficient sedation is provided orcontraindications exist for either spinal or general anesthesia.Then, local anesthesia with widespread infiltration around thesinus or fistula should be performed, carefully infiltrating inincrements from superficial to deep areas—towards the glute-al muscle fascia—and all around. Larger volumes of localanesthesia are usually needed because of the extensivenessof surgery, generally a total of 40 ml of a mixture ofbupivacaine 0.25%/lidocaine 1% mixture of 1:1.

All these blocks demand good collaboration between sur-geon and anesthesiologist. It is best performed with teams

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who know each other well and have done these proceduresunder these circumstances before. It is important to create acomfortable OR atmosphere for the patient and/or sufficientsedation. Excellent communication between all heath careproviders avoids failure and guarantees best outcome. In thesecircumstances, loco-regional techniques together with contin-uous sedation provide optimal pain relief during and aftersurgery for these kinds of open minor abdominal surgeries.

However, all these surgeries can also be done under generalanesthesia, most of them using a laryngeal mask airway. Ifthere are absolute or relative contraindications for the use ofthe laryngeal mask airway (LMA), then endotracheal intuba-tion can be used, such as for more obese patients or surgery inthe prone position. Some might argue that performing generalanesthesia in these patients might have a negative impact onthem leaving the hospital early or being done on an outpatientbasis. This can be true depending on how anesthesia is deliv-ered and how long surgery is. Modern techniques of generalanesthesia—total intravenous anesthesia using target-controlled infusion, monitoring of depth of anesthesia, usingshort-acting drugs, such as remifentanil, reduced, or no mus-cle relaxation—have greatly reduced not only the most com-mon side effect of general anesthesia in this setting, postoper-ative nausea, or vomiting, but also shortened significantly thelength of stay, both in the recovery room and in the hospitalallowing the vast majority of these types of surgery beingdone as an outpatient.

The most important aspect of early discharge and patientcomfort, however, is the combination of general anesthesiawith adequate multimodal pain relief strategies, includingthe combination of local analgesic techniques. Themore drugsare used, the higher the risk for having side effects. Not everypatient reacts well to receiving ketorolac as pain relief, some

suffer from side effects, such as upset stomach, nausea, orvomiting. However, these side effects are less frequent thanwhen opioids are used [7].

If general anesthesia is chosen to provide anesthesia forthese patients, great care should be taken to use short-actinganesthetic agents, and reverse the effects of muscle relaxantsefficiently, and use multimodal pain relief strategies, includingpre-emptive local analgesic strategies, local infiltration byanesthetist or surgeon before incision, or using loco-regionalblocks before start of surgery to limit the use of opioids in thepostoperative period.

It is a very common practice for surgeons to infiltrate thewound after surgery using longer-lasting local anesthetics.However, this is not the right strategy: local wound infiltrationshould be performed before incision, with the idea to haveoptimal local analgesia at the time the incision is performed.Knowledge of the onset profile of a given local anesthetic isimportant and very often lacking; also, time constraints withinthe operating room will press the surgeon to cut before thelocal anesthetic infiltration has not reached its speak effect yet.Onset time, not time to peak effect, for levobupivacaine, forexample, is 10–15 min: it would be uncommon to see thesurgeon inject preemptively levobupivacaine as a local infil-tration and then wait patiently for 15min before doing the skinincision.

It is therefore preferable if preemptive local anesthesia isperformed by the anesthetist, so that there is sufficient timebetween injection and incision—without wasting expensivetime in the operating room [8].

Using preemptive blocks, such as TAP block, RS block, orilioinguinal and iliohypogastric blocks, is another option,probably providing better postoperative analgesia than localinfiltration alone. Since surgery in this case is performed under

Fig. 3 US-guided ilioinguinal-iliohypogastric block. Ultrasoundimage of the anatomical structuresrelevant for the ilioinguinal andiliohypogastric block. The nervescan often be identified ashypoechogenic circular structuresbetween internal oblique andtransversus abdominis muscles

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general anesthesia, most anesthetists would decrease the con-centration of the local anesthesia used, while still using thesame volume: however, there is no fixed rule for this.

There are some types of surgeries in this list, pilonidalsinuses and ischiorectal abscess, where local infiltration tech-niques are not available or of limited or experimental value.Both types of surgeries are usually performed using generalanesthesia and multimodal drug pain relief strategies, e.g., acombination of intraoperative opioids, preemptive ketorolacat the end of surgery, and oral pain medication for the postop-erative period. It is the opinion of this author that these patientsgenerally benefit from a combination of these strategies withspinal anesthesia rather than general anesthesia, in order tobetter cover the immediate postoperative period.

Let us summarize a couple of exemplary case studies forthe different surgeries under general anesthesia plus local/regional pain techniques and pain drugs.

Umbilical hernia

Induction and maintenance of anesthesia as target-controlled infusion (TCI) of propofol, target-controlled infu-sion of remifentanil, brain monitoring to provide light level ofanesthesia; LMAwithout or reduced use of muscle relaxants.

Controlled ventilation or spontaneous respiration accord-ing to the anesthetic preference

BEFORE incision

Rectus sheath block bilaterally, using 20 ml bupivacaine0.125%, each side at least 15 min before surgery

AT end of surgery

Injection of ketorolac 30 mg intravenously (immediate on-set of peak effect, usually lasting for 6–8 h) [9]

Inguinal hernia

Induction and maintenance of anesthesia as TCI propofol,TCI remifentanil, brain monitoring to provide light level ofanesthesia; LMAwithout or reduced use of muscle relaxants.

Controlled ventilation or spontaneous respiration accord-ing the anesthetic preference

BEFORE incision

TAP block, using 20 ml bupivacaine 0.125%, at least15 min before surgery

AT end of surgery

Injection of ketorolac 30 mg intravenously

Hemorrhoid surgery

Induction and maintenance of anesthesia as TIVA-TCIpropofol, TCI remifentanil, brain monitoring to provide lightlevel of anesthesia; LMA without or reduced use of musclerelaxants.

Controlled ventilation or spontaneous respiration accord-ing the anesthetic preference

BEFORE incision

Local infiltration using 20 ml bupivacaine 0.125%, at least15 min before surgery, equally injected around the anal skin

AT end of surgery

Injection of ketorolac 30 mg intravenously

Surgery of ischiorectal abscess

Although there are studies showing a beneficial effect of localanesthesia on pain relief after anal surgery [10], one needs toremember that the efficacy of local anesthetics in areas ofinfection or inflammation is greatly reduced [11].

Surgery of pilonidal sinus-fistulas

Since the surgical site is usually not highly Binflamed orinfected,^ local anesthesia might be useful [12]. In the litera-ture, there is simply the description of injecting 20 ml of localanesthetics around the pilonidal sinus in the sacrococcygealregion.

Here is a possible alternative technique for general anes-thesia with local infiltration using a more plane typetechnique.

Induction and maintenance of anesthesia as TCI propofol,short-acting opioids, brain monitoring to provide light level ofanesthesia; endotracheal intubation with reduced use of mus-cle relaxants (since most of the surgeons prefer a proneposition).

Controlled ventilation

BEFORE incision

Plane block using US guidance: deposit of 15 mlbupivacaine 0.125%, at least 15 min before surgery, equallyinjected on each side, deposited just above the profoundglutaeus maximus muscle fascia. In addition, 5 mlbupivacaine 0.125% is injected below the skin, medially andcentered along the pilonidal sinus.

AT end of surgery

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Injection of ketorolac 30 mg intravenouslyOther than umbilical hernias, these open types of minor

abdominal surgery are suitable for spinal anesthesia.One of the main problems of spinal anesthesia, however, is

the occurrence of headaches as well as the risk of dural hema-toma; hence, the contraindication of its use when coagulationis impaired. Due to the increased and aggressive use of anti-coagulant drugs by cardiologists, there is also an increasingnumber of patients on these drugs. In the elective setting, thismight not be a problem since normal coagulation is restoredbefore surgery and therefore spinal anesthesia can be used. Inthe emergency setting, e.g., incarcerated hernias orischiorectal abscesses, this is not the case. Spinal anesthesiacannot be used. General anesthesia plus loco-regional tech-niques are a good choice here.

The advantage of spinal anesthesia in the immediate post-operative period is the complete analgesia in the first hoursafter surgery. However, since spinal blockade also limits trans-fer from the recovery room and affects spontaneous urination,discharge from the hospital might also be delayed.

Two main types of spinal anesthesia are available and theiruse depends on the type and length of surgery, as well as thepreference of the anesthesiologist.

Lidocaine, formerly a popular choice for short-acting spi-nal anesthesia, has lost its place due to the inherent risk oftransient neurologic symptoms (TNS). Other more modernshort-acting local anesthetics, such as articaine or prilocaine,are not available in all countries for these indications. Thisleaves the anesthesiologist with the safest choice as spinalanesthesia with isobaric or hyperbaric long-acting local anes-thetics, such as bupivacaine or levobupivacaine [13].

Isobaric spinal anesthesia provides the advantage of notwasting OR time before surgery, while hyperbaric spinal an-esthesia offers the advantage of faster recovery time, shortertime in the recovery room, and ultimately earlier dischargefrom the hospital.

Adding about 5 min of Bfixation^ time when hyperbaricspinal anesthesia is used can easily shorten 1–2 h of time in therecovery room [14].

There is also some debate whether there is less urinaryretention with hyperbaric than isobaric spinal anesthesia, andthe duration of leaving the patient in a given position is debat-able, from 3 to 10 min usually, to as short as 1 min [15].

Generally speaking, hyperbaric spinal anesthesia involvesa bit more Btiming^ and might not offer significant advantagesin terms of urinary retention; however, the duration of motorand sensory block is significantly shorter. Some anesthesiolo-gists experience patients to be more prone to hypotension withhyperbaric spinal anesthesia than isobaric anesthesia althoughnot objectively proven [14].

As a rule of thumb, spinal anesthesia can be performedwithalmost 100% success in terms of sufficient analgesia for alltypes of minor abdominal open surgery using 2 cc of isobaric

bupivacaine 0.5% or equivalent doses of other local anes-thetics, or 1 cc of hyperbaric bupivacaine 0.75%.

In the author’s experience, a Bpositioning^ time of 5 min issufficient in the vast majority of patients.

In terms of postoperative analgesia, similar strategies to theones mentioned in the section of general anesthesia are impor-tant. Postoperative analgesia should be provided before thespinal anesthesia has worn off.

Most studies have shown that spinal anesthesia providesbetter pain relief in the immediate postoperative period versusgeneral anesthesia with no difference in the latter stages aftersurgery [16, 17].

However, especially in younger patients, this benefit mightbe outweighed by the risk of post spinal headache.

One particular clinical problem is managing biggeringuinoscrotal hernias, especially in cases where bowel iswithin the scrotal sac and which then during surgery will thenhave to be pulled back into the abdominal cavity.

It is this author’s experience that both loco-regional tech-niques as well as spinal anesthesia often are not sufficient andadequate. Pulling on the intestines and reflex activation of theperitoneum can often lead to significant pain more cranially orsignificant vagal reaction. The author’s preference is to per-form these big hernias using general anesthesia combinedwith either TAP or ilioinguinal/iliohypogastric blocks.

Recently, many minor abdominal surgeries are performedlaparoscopically, namely the repair of hernias. This presentsnew challenges for the anesthesiologist as these types of sur-gery cannot be performed using loco-regional techniques orneuraxial anesthesia alone.

In addition, laparoscopic surgery is prone to cause moreoften postoperative nausea and vomiting; hence, intraopera-tivemanagement should focus on trigger-free general anesthe-sia, e.g., propofol anesthesia without nitrous oxide. The pneu-moperitoneum can cause significant postoperative pain in awide area; very often patients complain postoperatively ofpain close to the insertion ports, the bigger the insertion portthe more likely it is to cause pain.

The best pain strategy is a multiple regiment pain reliefeffort given before the end of surgery combined with TAPblock right after induction of anesthesia [18].

In the author’s experience, it is best to insert the needle at alevel of T11–T12 and opt for bigger volume and lower con-centrations; e.g., 30 ml bupivacaine 0.125% injected on eachside provides analgesia in T10-L1 nerve endings.

However, since pneumoperitoneum covers a wider areathan just T10-L1, one should not be surprised that the TAPblock alone is not sufficient to cover all postoperative pain,hence the need for an adequate multimodal pain strategy. It isalso interesting to note that although classified as Bminimallyinvasive surgery,^ a great number of patients will experiencesignificant pain as usually experienced after open surgeryonly.

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Some studies have found sufficient analgesia when RS isperformed for these types of surgeries, although this authorwould suggest TAP blocks [19].

Particular laparoscopic surgeries

Laparoscopic appendicectomy

Laparoscopic appendicectomy must be performed under gen-eral anesthesia. The new gold standard for appendicectomypresents considerable challenges for the anesthetist: it is usu-ally a short procedure necessitating a rather profound level ofmuscle relaxation and produces—since it is an inflammatoryemergency—significant postoperative pain. Effective pain re-lief starts with sufficient intraoperative analgesia, with opioiddoses generally higher than one would expect for minor lap-aroscopic procedures. A multimodal postoperative pain strat-egy is the basis for sufficient pain relief.

Recent studies have focused on efficacy of abdominal wallblocks for pain relief and have been somewhat inconclusivewith studies showing no effect of TAP blocks [20–23] oversimple port-site local anesthesia. However, there are few stud-ies showing a significant benefit if TAP block is part of amultimodal pain strategy in children undergoing laparoscopicappendicectomy [24] as well as in open appendicectomy,which is rarely performed nowadays [25–27].

As a standard practice, this author would not recommendapplying TAP blocks for laparoscopic appendicectomy but foropen appendicectomy only. Remifentanil or fentanyl intraop-eratively, ketorolac before the end of surgery, and acetamino-phen after surgery are all part of a multimodal pain reliefstrategy.

Laparoscopic cholecystectomy

Similar strategies are necessary for laparoscopic cholecystec-tomy, which is the gold standard nowadays for elective orurgent cholecystectomy. In fact, open cholecystectomy usual-ly only occurs as a complication of failed laparoscopic attemptand presents a significant challenge for postoperative painmanagement, usually necessitating either morphine IVor con-trolled by the patient or even sometimes a high thoracic epi-dural analgesia for pain control.

In laparoscopic cholecystectomy, most studies have shownno benefit of conventional TAP block as part of a multimodalstrategy and no significant advantage over port infiltration [28,29]. However, subcostal TAP block might actually providebeneficial analgesia [30–34].

The subcostal TAP blocks anesthetizes the intercostalnerves T6–T9 between the rectus abdominis sheath and thetransversus abdominis muscle. The approach necessitates

oblique positioning of the US probe just beneath the rib cage,on the right side [35].

As in a standard TAP block, 20–30 ml of local anestheticsshould be administered before surgery.

In summary, laparoscopic appendicectomy and cholecys-tectomy present various challenges for the pain management;both are usually emergency surgeries with a strong componentof local inflammation or even general septicemia. This impliesusually an upregulation of pain receptors, which makes painmanagement more difficult; surgery time is usually short atless than 60min. From a perioperative pain management pointof view, a key aspect is sufficient intraoperative analgesia—either remifentanil or fentanyl with the majority of the dosegiven at induction and titrated to the end—with narcotic needsusually more than expected, and a sufficient multimodal painstrategy, including ketorolac or acetaminophen. Standard TAPblock might be considered for open appendicectomy only,subcostal TAP block for laparoscopic cholecystectomy, bothadministered before surgery.

If closed cholecystectomy turns to open, then more elabo-rate pain strategies might be considered, such as TEA or PCAusing opioids since considerable pain can be expected.

Repair of incisional hernia

Incisional hernias cannot easily be classified; depending onthe size and location of defect, surgery—and associatedpain—can resemble the repair of a simple umbilical herniaor a full median laparotomy. In addition, there is no clearconsensus between surgeons which technique to use in whichpatient [36].

However, there is clearly a tendency towards laparoscopicrepair, with it being more cost effective, associated with re-duced length of stay, number of outpatient visits, and estimat-ed days off [37].

Therefore, the choice of pain strategy depends on the typeof surgery—open versus closed—and size of incision and/ordefect. Multimodal pain strategy can therefore be either sim-ilar to pain management of an open umbilical hernia or openmajor abdominal surgery.

Major abdominal surgery

As for minor abdominal surgery, laparoscopic surgery hasbecome more and more popular even for the most complexabdominal surgeries; however, not all surgeons use laparo-scopic techniques for major abdominal surgeries, nor is it con-sidered the gold standard. Therefore, pain management needsto be adapted to all types of approaches, be it open or closed,depending on the surgeon’s preference.

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Open major abdominal surgery

Preferred access is median laparotomy in various degrees ofincision lengths and placements depending on the site of sur-gery and individual surgeon. For many decades, thoracic epi-dural analgesia has been the gold standard of perioperativepain management [38].

Not only does TEA provide excellent analgesia, but it canalso be beneficial for recovery of gut function, reduce pulmo-nary, cardiovascular, thromboembolic, and gastrointestinalcomplications occurring after abdominal surgery.

It is important to know that lumbar epidural catheters donot provide these additional benefits. To the contrary, lumbarepidurals can actually impair recovery since it can make mo-bilization of the patient difficult. Depending on the incisionsite, TEA should be placed in the lower or middle thoracicregion and used perioperatively, as a continuous infusion oflocal anesthetics, with or without adjuncts such as clonidine oropioids. It is important that TEA is followed either by ananesthesiologist or a dedicated pain service to adjust dosesaccording to the development of pain after surgery, as wellas the degree of patient mobilization, and recognize and con-trol possible complications, such as epidural hematoma. Therisk of developing such a hematoma is considered to bearound 1:6600 [39] but increases if there is insufficient coop-eration between the health care providers, e.g., a surgeonwould prescribe heparin, without the anesthesiologist’sknowledge, and a catheter be removed under heparin—thuscreating the risk of an epidural hematoma.

A practical approachwould be the following TEA regimen:installation of TEA before surgery, starting of TEA at 10 ml/hof bupivacaine 0.065% with 3 microg/ml of fentanyl for 3–5 days titrated to the pain between 4 and 16 ml/h. If pain ismore than 4/10, then the TEA infusion rate is increased by1 ml/h, if pain is absent, reduce infusion rate by 1 ml/h. Safetyinstructions and standardized protocols are preeminent forusing TEA in safe conditions and all health care providersmust be aware of the catastrophic complication of epiduralhematoma and how to act in this emergency situation.

Supplemental multimodal pain medication is equally im-portant as enrolment in a fast track program; studies haveshown that enrolment in such a program alone can have anal-gesic effects.

However, epidural analgesia has been associated with lon-ger hospital stay and higher hospital costs, and more urinarytract infections [40]. Also; this might be due to the use oflumbar epidural analgesia rather than thoracic epidural anal-gesia. This might be the reason for increased postoperativeileus [41].

However, there is an increasing number of recent studiesshowing difficulties with using epidural analgesia in the sce-nario of colorectal surgery, mostly in terms of urinary reten-tion, longer hospital stay, and problems of management of

anticoagulation therapy [42, 43]. In times, whereanticoagulation therapy affects more patients, and is more ag-gressive, and major abdominal surgery is increasingly per-formed laparoscopically, the use of TEA is reduced. A meta-analysis from 2018 provided moderate evidence for equallyeffective analgesia of TAP blocks and epidural analgesia, withfewer episodes of hypotension with TAP blocks [44]. A recentstudy confirmed this tendency even in esophagectomy [45].Better overall analgesic efficacy and less hypotension aftersurgery with TAP blocks in comparison to thoracic epiduralanalgesia were reported for major abdominal oncologic resec-tions [46].

Laparoscopic major abdominal surgery

This type of surgery differs in terms of Bpain^ area from thelaparoscopic approach described for minor abdominal sur-gery, such as laparoscopic hernia repair, in such a way thatin order to remove the dissected colon, a small incision mustbe made. So in addition to the small incision holes found inminor abdominal laparoscopic surgery, an additional incisionof 5–10 cm is made and the bowel removed.

One experiences that the pain intensity is increased andpain treatment is more difficult.

Studies have shown that bilateral TAP blocks are beneficialin a multimodal pain strategy after laparoscopic colorectalsurgery [47]. This author prefers to perform the TAP blocksin close proximity to the intended site of Bincision to removethe bowel^ to optimize the pain strategy. The usual 25–30 mlof low concentration local anesthetics is sufficient to providegood pain relief within a strategy of postoperative low-doseopioids, NSAIDs, and other supplemental analgesia.

A relatively new technique is continuous TAP blocks viacatheters, bilaterally inserted. There is the advantage of pro-viding continuous local anesthesia, both either via continuousinfusion of, for example, 8 ml/h ropivacaine 0.2% each site, oras intermittent boli of 20 ml of ropivacaine 0.2% each siteevery 8 h. The disadvantage of this technique is that the cath-eter can only be inserted after surgery—because otherwise ofbeing within the surgical sterile field—so sufficient intraoper-ative analgesia is necessary.

In this author’s practice, TAP block—continuously or assingle-shot—has almost replaced TEA for colorectal surgery,other than for specific indications, such as chronic pulmonarydisease.

One can say that in the last decade, there is a paradigm shiftboth for open or closedmajor abdominal surgery from TEA asthe gold standard of perioperative pain control towards moremodern forms of less invasive techniques, with the main focuson TAP blocks. Studies have shown that continuous TAPblocks can be as efficient in terms of pain control as continu-ous epidural analgesia [48–50], which leaves us with the

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question when to use single-shot TAP block versus continu-ous TAP block.

Is there a difference in pain after open versus closed majorabdominal surgery [51]?

Pain peaks after laparoscopic surgery occur mostly withinthe first 24 h; pain peaks after open surgery occur during thefirst 72 h, mostly during mobilization.

Single-shot TAP blocks are therefore sufficient for patientsundergoing laparoscopic major abdominal surgery with an

Table 1 Pain management per type of surgery—an empirical approach

Minor open surgery

Umbilical hernia

1st choice

Bilateral rectus sheath block 20 min before surgery under short-termsedation (midazolam or propofol)

Example: 2 × 20 ml of a 1:1 mixture of lidocaine 1%/bupivacaine 0.25%

Intraoperative sedation using TCI-TIVA propofol titrated to BIS between75 and 85

Ketorolac 30 mg IV at the end of surgery

Postoperatively

Most often, no additional medication necessary; if yes, fentanyl25–50 microg IV in the PACU; 650 mg acetaminophen BID

Inguinal hernia

1st choice

Bilateral transversus abdominis plane block 20 min before surgery undershort-term sedation (midazolam or propofol)

Example: 2 × 20 ml of a 1:1 mixture of lidocaine 1%/bupivacaine 0.25%

Intraoperative sedation using TCI-TIVA propofol titrated to BIS between75 and 85

Ketorolac 30 mg IV at the end of surgery

Postoperatively

Most often, no additional medication necessary; if yes, fentanyl25–50 microg IV in the PACU; 650 mg acetaminophen BID

Hemorrhoid surgery

1st choice

TCI-TIVA propofol, fentanyl, low-dose rocuronium to facilitate LMAplacement, controlled ventilation using LMA

After induction of anesthesia

Local anesthesia using 15 ml of 1:1 mixture of lidocaine 1%/bupivacaine0.25%, injected around anus

Ketorolac 30 mg IV at the end of surgery

Postoperatively

Most often, no additional medication necessary; if yes, fentanyl25–50 microg IV in the PACU; 650 mg acetaminophen BID

Repair of pilonidal sinus in the prone position

1st choice

Spinal anesthesia

After spinal anesthesia and before surgery

Local anesthesia both sides of the pilonidal sinus: 2 × 20 ml 1:1 mixtureof lidocaine 1%/bupivacaine 0.25%

Ketorolac 30 mg IV at the end of surgery

Postoperatively

Table 1 (continued)

Most often no additional medication necessary; if yes, fentanyl 25–50 microg IV in the PACU; 650 mg acetaminophen BIDMinor laparoscopic surgeryInguinal, incisional, or umbilical herniaTCI-TIVA propofol, fentanyl, full relaxation using rocuronium,controlled ventilation using endotracheal intubationBilateral transversus abdominis plane block before surgeryExample: 2 × 20 ml of a 1:1 mixture of lidocaine 0.5%/bupivacaine0.125%Ketorolac 30 mg IVat the end of surgeryPostoperativelyFentanyl 25–50 microg IV in the PACU; 650 mg acetaminophen orallyBIDLaparoscopic appendicectomyTCI-TIVA propofol, fentanyl, full relaxation using rocuronium,controlled ventilation using endotracheal intubationNote to give sufficiently intraoperative opioidsKetorolac 30 mg IVat the end of surgeryPostoperativelyFentanyl 25–50 microg IV in the PACU; 650 mg acetaminophen orallyBIDLaparoscopic cholecystectomyTCI-TIVA propofol, fentanyl, full relaxation using rocuronium,controlled ventilation using endotracheal intubationNote to give sufficiently intraoperative opioidsAfter induction of anesthesia, before surgerySubcostal transversus abdominis plane block before surgeryExample: 20 ml of a 1:1 mixture of lidocaine 0.5%/bupivacaine 0.125%Ketorolac 30 mg IVat the end of surgeryPostoperativelyFentanyl 25–50 microg IV in the PACU; 650 mg acetaminophen orallyBIDMajor open surgeryColorectal surgeryOne choiceInstallation of TEA and start of continuous infusion of bupivacaine0.065% with 2 microg/ml fentanyl at 6–10 ml/h; to be continued for 72 hTCI-TIVA propofol, fentanyl, full relaxation using rocuronium,controlled ventilation using endotracheal intubationKetorolac 30 mg IVat the end of surgeryPostoperatively650 mg acetaminophen orally QID for 3 daysAlternative choiceTCI-TIVA propofol, fentanyl, full relaxation using rocuronium,controlled ventilation using endotracheal intubationInstallation of continuous bilateral TAP blocks immediately after surgery;continuous infusion of Naropin 0.2% at 8 ml/h each sideKetorolac 30 mg IVat the end of surgeryPostoperatively650 mg acetaminophen orally QID for 3 daysPCA fentanyl for 3 daysMajor laparoscopic surgeryColorectal surgeryTCI-TIVA propofol, fentanyl, full relaxation using rocuronium,controlled ventilation using endotracheal intubationBilateral transversus abdominis plane block before surgeryExample: 2 × 20 ml of a 1:1 mixture of lidocaine 1%/bupivacaine 0.25%Ketorolac 30 mg IVat the end of surgeryPostoperatively650 mg acetaminophen orally QID for 3 daysPCA fentanyl for 3 days if necessary

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expected analgesia of up to 24 h, whereas continuous TAPblocks are used in open abdominal surgery where significantpain is expected to occur for several days after surgery.

Both techniques are combined with a multimodal analgesiastrategy, ketorolac 30 mg IV at the end of surgery, and orallyadministered acetaminophen or paracetamol QID for 2 days.In addition, PCA with a short-acting opioid such as fentanylcan be used if necessary.

Patients treated with TAP blocks undergoing laparoscopiccolon surgery showed lower postoperative nausea andvomiting, lower rates of postoperative ileus, and paresthesiawhen compared with patients with thoracic epidural analgesia[52].

Conclusion

The basis of efficient pain relief during abdominal surgery is amultimodal strategy, a combination of loco-regional analgesictechniques combined with short-acting opioids, NSAIDs, andsupplemental drugs, such as acetaminophen.

Thoracic epidural analgesia has lost its status as the goldstandard for major abdominal surgery with the introduction ofalternative local techniques, specifically abdominal wallblocks, and the trend towards laparoscopic surgery. In addi-tion, recent advancement and developments of aggressiveanticoagulation medication used for a variety of indicationsas well as recent studies questioning the overall benefit ofTEA both in terms of superior pain relief but also its negativeimpact on mobilization—patient and bowel—and spontane-ous urinary output have shifted the risk-benefit balance awayfrom TEA.

Minor open abdominal surgery, from open inguinal herniarepair to hemorrhoid surgery, can easily be performed under avariety of abdominal wall blocks and local field blocks, TAP,RS, ilioinguinal-iliohypogastric blocks only with efficientcontinuous sedation, best titrated to a given objective state ofsedation (brain monitoring). These strategies guarantee thebest risk-benefit ratio, allowing surgery with optimal analgesiaand early hospital discharge. Collaboration between all healthcare providers is essential for the success of these strategies.

Spinal anesthesia can no longer be considered as the firstanesthesia choice for open minor abdominal surgery.Abdominal wall blocks can be used as an efficient and prob-ably main component of a multimodal strategy for pain reliefwhen general anesthesia is necessary for minor laparoscopicsurgery. Laparoscopic appendicectomy does not benefit fromabdominal wall blocks; a standard conservative multimodalstrategy consisting of NSAIDS and opioids is efficient.

Subcostal TAP blocks have shown to be beneficial for lap-aroscopic cholecystectomies as part of a multimodal strategy.

Major laparoscopic abdominal surgery, such as laparoscop-ic colon resections, will mostly benefit from a combined

strategy of bilateral single-shot TAP blocks before surgery,sufficient opioid administration during surgery—e.g., contin-uous remifentanil or fentanyl with the majority of fentanylgiven in the beginning and tailoring off towards the end ofsurgery—administration of IV ketorolac before the end ofsurgery and oral NSAIDs plus PCA fentanyl after surgery.Most of the pain will be gone within 24 to 48 h postsurgery.

Major open abdominal surgery will benefit from a multi-modal pain strategy including continuous TAP block installedafter surgery. Thoracic epidural analgesia should be reservedfor specific indications such chronic pulmonary disease.

Spinal anesthesia should be reserved for anal surgery if patientor surgeon does not accept local techniques. It also still has aplace in repair of ischiorectal abscesses or pilonidal sinus surgery,where postoperative immediate pain can be severe, local anes-thesia tends to fail due to the significant inflammation.

Pain management in abdominal surgery needs to be adjust-ed for each type of surgery to find the best possible option(Table 1).

Acknowledgements The author thanks the Department of GeneralSurgery at Fleury Hospital for their precious collaboration during thedevelopment of a modern multimodal pain strategy. He is also gratefulto his colleagues Drs Chaveron and Errouissi for their enthusiasm andcreativity to implement these strategies. Lastly, many thanks to the nursesof the PACU of Fleury Hospital for their dedication and help.

Compliance with ethical standards

Conflict of interest The author declares that he has no conflict ofinterest.

Ethical approval This article does not contain any studies with humanparticipants performed by any of the authors.

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